1. Chapter 13 – Part 1 The Respiratory System

2. Organs of the Respiratory system
Nose
Pharynx
Larynx
Trachea
Bronchi
Lungs – alveoli

3. Function of the Respiratory System
Oversees gas exchanges between the blood and external environment
Exchange of gasses takes place within the lungs in the alveoli
Passageways to the lungs purify, warm, and humidify the incoming air

4. The Nose The only externally visible part of the respiratory system
Air enters the nose through the external nares (nostrils)
The interior of the nose consists of a nasal cavity divided by a nasal septum

5. Figure 13.2

6. Anatomy of the Nasal Cavity
Olfactory receptors for the sense of smell are located in the mucosa on the slitlike superior part of the nasal cavity
The rest of the cavity is lined with respiratory mucosa
Warm the air
Moistens the air
Traps incoming foreign particles (cleanse)

7. Anatomy of the Nasal Cavity
The ciliated cells of the nasal mucosa create a gentle current that moves contaminated mucous posteriorly towards the throat (pharynx)
It is then swallowed and digested by stomach juices.
When it is extremely cold, these cilia become sluggish, allowing mucus to accumulate in the nasal cavity and to dribble outward through the nostrils.
This is why you have a “runny” nose on a cold day.

8. Nosebleeds
The respiratory mucosa rests on a rich network of thin-walled veins (warms the air as it flows by).
Because of the superficial location of these blood vessels, nosebleeds are common and often profuse.

9. Anatomy of the Nasal Cavity
The lateral walls of the nasal cavity have three projections or lobes called conchae
Increases surface area
Increases air turbulence within the nasal cavity
Helps to deflect inhaled particles onto the mucus-coated surfaces, where they are trapped and prevented from entering the lungs.

10. Anatomy of the Nasal Cavity
The nasal cavity is separated from the oral cavity by the palate
Anterior hard palate (bone)
Posterior soft palate (muscle)

11. Cleft Palate
Cleft palate – The bones forming the palate fail to fuse medially
Genetic defect
Results in breathing difficulties and problems with oral cavity functions (chewing and speaking)

12. Paranasal Sinuses
The nasal cavity is surrounded by a ring of paranasal sinuses.
Are located in the:
Frontal bone
Sphenoid bone
Ethmoid bone
Maxillary bone

13. Paranasal Sinuses Function of the sinuses Lighten the skull
Act as resonance chambers for speech
Produce mucus that drains into the nasal cavity
The suctioning effect created by nose blowing helps to drain the sinuses.
The nasolacrimal ducts, which drain tears from the eyes, also empty into the nasal cavities

14. Sinusitis Sinusitis – sinus inflammation Difficult to treat
Can cause marked changes in voice quality
When the passageways connecting the sinuses to the nasal cavity are blocked with mucus or infectious matter, the air in the sinus cavities is absorbed
The result is a partial vacuum and a sinus headache

15. Pharynx (Throat)
Pharynx - Muscular passage from nasal cavity to larynx
About 5 inches long
Commonly called the throat
Serves as a common passageway for food and air
Is continuous with the nasal cavity anteriorly via the internal nares

16. Pharynx (Throat) Three regions of the pharynx:
Nasopharynx – superior region behind nasal cavity
Oropharynx – middle region behind mouth
Laryngopharynx – inferior region attached to larynx
The oropharynx and laryngopharynx are common passageways for air and food
Air then passes through the larynx, while food is directed into the esophagus posteriorly

17. Structures of the Pharynx
The auditory tubes, which drain the middle ear, open into the nasopharynx
Since the mucosae of these two regions are continous, ear infections may follow a sore throat or other types of pharyngeal infections

18. Structures of the Pharynx
Tonsils (clusters of lymphatic tissue) are also found in the pharynx
Their job is to trap and remove any bacteria or other foreign pathogens entering the throat
Pharyngeal tonsil – located high in the nasopharynx
Palatine tonsils – located in the oropharynx at the end of the soft palate
Lingual tonsils – located at the base of the tongue

20. Tonsillitis
Tonsillitis – Inflammation and swelling of the pharyngeal tonsil
Can occur during a bacterial infection
It obstructs the nasopharnyx and forces the person to breathe through the mouth
In mouth breathing, air is not properly moistened, warmed, or filtered before entering the lungs
Years ago, the belief was that the tonsils were more trouble than they were worth and they were routinely removed.
Now, this is no longer necessary because of the large use of antibiotics

21. Larynx (Voice Box) Functions of the Larynx:
Routes air and food into proper channels
Plays a role in speech (voice production)
Acts as an airway
Made of eight rigid hyaline cartilages and a spoon-shaped flap of elastic cartilage (epiglottis)

22. Structures of the Larynx
Thyroid cartilage
Largest hyaline cartilage
Shield-shaped
Protrudes anteriorly
Commonly called the Adam’s apple

23. Structures of the Larynx
Epiglottis
Protects the superior opening of the larynx
Routes food to the esophagus and air toward the trachea
The epiglottis moves positions when swallowing
When we are not swallowing: the epiglottis does not restrict the passage of air into the lower respiratory passages
When we are swallowing: the larynx is pulled upward and the epiglottis tips, forming a lid over the opening of the larynx; this routes food into the esophagus

24. Structures of the Larynx
Palpate your larynx by placing your hand midway on the anterior surface of your neck. Swallow. Can you feel the larynx rising as you swallow?

25. Cough Reflex
If anything other than air enters the larynx, a cough reflex is triggered to expel the substance and to prevent it from continuing into the lungs.
Because this protective reflex does not work when we are unconscious, it is never a good idea to try to give fluids to an unconscious person when attempting to revive him or her.

26. Structures of the Larynx
Vocal cords (vocal folds)
Pair of folds
Vibrate with expelled air to create sound
Allows us to speak
Glottis – the slitlike passageway between the vocal cords

28. Trachea (Windpipe) Connects larynx with bronchi About 4 inches long
Lined with ciliated mucosa
Beat continuously in the opposite direction of incoming air
Propels mucus loaded with dust and other debris away from lungs to the throat, where it can be swallowed or spat out

29. The Trachea and Smoking
Smoking inhibits ciliary activity and ultimately destroys the cilia
Without these cilia, coughing is the only means of preventing mucus from accumulating in the lungs

30. Trachea (Windpipe)
The trachea is fairly rigid because its walls are reinforced with C-shaped hyaline cartilage
These rings form two purposes:
Support the trachea and keep it open in spite of the pressure changes that occur during breathing
Allows it to expand anteriorly when we swallow a large piece of food

31. Heimlich Maneuver
Heimlich maneuver – a procedure in which the air in a person’s own lungs is used to “pop out,” or expel, an obstructing piece of food
Because the trachea is the only way air can get into the lungs, tracheal obstruction is life- threatening
Many people have suffocated after choking on a piece of food that suddenly closed off the trachea
Has saved many people from choking to death

32. Primary Bronchi
The right and left primary bronchi is formed by the division of the trachea
Enters the lung at the hilus (medial depression)
Right bronchus is wider, shorter, and straighter than left
Consequently it is the more common site for an inhaled foreign object to become lodged
Bronchi subdivide into smaller and smaller branches
By the time air enters the bronchi, it is warmed, cleansed of most impurities, and well humidified

34. Lungs The paired lungs are fairly large organs
Occupy most of the thoracic cavity
Apex is near the clavicle (narrow, superior portion)
The broad base rests on the diaphragm (inferior portion)
The bronchi enters the lung at the hilus (medial depression)

36. Lungs Each lung is divided into lobes by fissures
Left Lung - Has two lobes
Right Lung - Has three lobes

37. Coverings of the Lungs
Pulmonary (visceral) pleura covers the lung surface
Parietal pleura lines the walls of the thoracic cavity
Pleural fluid fills the area between layers of pleura to allow gliding during breathing movements
Can slide easily from side to side across one another, but resists being pulled apart.

38. Lungs

39. Coverings of the Lungs Pleurisy – Inflammation of the pleura
Can be caused by the decreased secretion of pleural fluid
The pleural surfaces become dry and rough
Results in friction and stabbing pain with each breath

40. Respiratory Tree Divisions
This branching and rebranching within the lungs is often referred to as the bronchial or respiratory tree:
Primary bronchi
Secondary bronchi
Tertiary bronchi
Bronchioles
Terminal bronchioles

41. Bronchioles Bronchioles - Smallest branches of the bronchi
All but the smallest branches have reinforcing cartilage

42. Bronchioles
Terminal bronchioles end in alveoli, or air sacs.

43. Respiratory Zone The respiratory zone is the only site of gas exchange
Includes the following structures:
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
All other respiratory passages are conducting zone structures
Serve as conduits to and from the respiratory zone.

44. Alveoli
There are millions of the clustered alveoli, which resemble bunches of grapes.
They make up the bulk of the lungs
Consequently, the lungs are mostly air space
In spite of their relatively large size, the lungs weigh only about 2 ½ pounds, and they are soft and spongy

45. Alveoli Structure of alveoli Alveolar duct Alveolar sac Alveoli
Gas exchange takes place within the alveoli in the respiratory membrane

46. Alveoli Structure of alveoli Alveolar duct Alveolar sac Alveoli
Gas exchange takes place within the alveoli in the respiratory membrane

47. Respiratory Membrane
Respiratory Membrane (Air-Blood Barrier) – Has gas (air) flowing past on one side and blood flowing past on the other
Made up of the alveolar and capillary walls and their fused basement membranes.

48. Respiratory Membrane
The walls of the alveoli are composed largely of a single, thin layer of squamous epithelial cells
The thinness of their walls is hard to imagine, but a sheet of tissue paper is much thicker
The external surfaces of the alveoli are covered with a “cobweb” of pulmonary capillaries

49. Respiratory Membrane
Alveolar pores connect neighboring air sacs and provide alternate routes for air to reach alveoli
In case feeder bronchioles have been clogged by mucus or otherwise blocked

50. Gas Exchange
Gas exchanges occur by simple diffusion through the respiratory membrane
Oxygen enters the blood
Carbon dioxide enters the alveoli
The total gas exchange surface provided by the alveolar walls is 40 times greater than the surface of your skin

51. Gas Exchange
The final line of defense for the respiratory system is in the alveoli
Macrophages wander in and out of the alveoli picking up bacteria, carbon particles, and other debris
Surfactant coats the gas-exposed alveolar surfaces
Lowers the surface tension of the film of water lining each alveolar sac so that the alveoli do not collapse between each breathe

52. Respiratory Membrane (Air-Blood Barrier)